mpc recording functions

hi guys am a newbi
and am having trouble recording my samples in the mpc

i recorded a bass track on track one, and now i want to add drums
but everyttime i swicth the program to add drums on top of my bass
the bass sound turn into drum sounds. am looking in the menual
andi cant find a thing.

change the track before changing the pgm.

grat looks thaks man

my bad i didnt get i thought i had it
i read the menual
and so far this is were am at

i went to save on the mpc i pressed ''Do it''
then i went to load and i didnt see it
also i went to the main menu and i still could hear the samples i dropped in my mpc from my mac

sorry wrong post this i understand